One of the first things many of us look at when buying a new phone is battery life. A low battery notification sends us into a panic. Losing your charger is a disaster. So, imagine a phone that would run without a battery. It seems like a crazy idea but it is actually being developed in a lab at the University of Washington, Seattle.
Vamsi Talla is a research associate who has been working on a prototype cell phone at the lab of Joshua Smith, a computer science and electrical engineering at UW. The aim is the develop a phone that can still make calls and texts, even when the battery runs out. To do so, a re-think of how phones operate was required and the phone would need to rely on energy that came from sources in the environment rather than the battery.
Solar panels or photodiodes can turn light into electricity and an antenna can convert radio-frequency TV and Wi-Fi broadcasts into energy. Those two sources can generate a small number of microwatts, which is nowhere near enough the 800 milliwatts required to make a simple call.
The lab had to firstly develop a technique called backscatter to communicate by reflecting incoming radio waves. Collecting enough power to convert human speech into a digital signal is problematic and analogue technology is more power-efficient. The phone can use a digital signal to dial numbers but using backscatter for voice calls means it is utilising analogue technology.
The phone with no battery is still a long way off. It has a touch-sensitive number pad and a tiny red LED. To operate as a touchscreen phone it would need over 100,000 times as much as Talla’s phone needs. It functions more like a walky-talky than a phone, with buttons being pressed in order to talk to the caller and a lot of static. They’re working on a next generation device with an E-Ink display and possibly a camera.
To read more about this, visit the story’s page on Wired.